C# - Regular Expression validating Date and Hour

Question

I receive Date and time from CSV file

The received Date format is  YYYYMMDD (string) (there is no ":" ,"-","/" to 
separate  Year month and date).

The received time format is HH:MM (24 Hour clock).

I have to validate both so that (example) (i) 000011990 could be invalidated for date (ii) 77:90 could be invalidated for time.

The question is ,

Regular expression is the right candidate for do so (or) is there any other way to achieve it?

Answer 1

I think a better way would be to use the date format class built into C#: DateTime.parse

Answer 2

Your easiest solution would be to use

DateTime output;
if(!DateTime.TryParse(yourstring, out output))
{ 
   // string is not a valid DateTime format
}

The DateTime.TryParse will attempt to convert your string to a DateTime variable, but it won't throw an exception if it fails - rather it return false if the string is not recognized as a valid DateTime.

Answer 3

You can use one of the TryParse methods of the DateTime struct. They will return false if they fail to parse.

Another option it use the ParseExact methods, but for those you need to specify a format provider.

Answer 4

You're looking for DateTime.TryParseExact:

string source = ...;
DateTime date;
if (!DateTime.TryParseExact(source, 
                            "yyyyMMdd", 
                            CultureInfo.InvariantCulture, 
                            DateTimeStyles.None, 
                            out date)) {
    //Error!
}

You can use the same code to validate times, with the format string "HH:mm".